CMOS implementation of germanium and III-V nanowires and nanoribbons in gate-all-around architecture

ABSTRACT

Architectures and techniques for co-integration of heterogeneous materials, such as group III-V semiconductor materials and group IV semiconductors (e.g., Ge) on a same substrate (e.g. silicon). In embodiments, multi-layer heterogeneous semiconductor material stacks having alternating nanowire and sacrificial layers are employed to release nanowires and permit formation of a coaxial gate structure that completely surrounds a channel region of the nanowire transistor. In embodiments, individual PMOS and NMOS channel semiconductor materials are co-integrated with a starting substrate having a blanket layers of alternating Ge/III-V layers. In embodiments, vertical integration of a plurality of stacked nanowires within an individual PMOS and individual NMOS device enable significant drive current for a given layout area.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a U.S. National Phase application under 35 U.S.C.§371 of International Application No. PCT/US2011/065914, filed Dec. 19,2011, entitled CMOS IMPLEMENTATION OF GERMANIUM AND III-V NANOWIRES ANDNANORIBBONS IN GATE-ALL-AROUND ARCHITECTURE.

TECHNICAL FIELD

Embodiments of the present invention generally relate to microelectronicdevice architecture and fabrication, and more particularly toheterogeneous nanowire transistors for CMOS.

BACKGROUND

Silicon CMOS technology has been the mainstay of microelectronics fordecades past. However, Moore's Law will at some point require extensionbased on non-silicon device technology. While microelectronic deviceshave long been fabricated in materials other than silicon, such as groupIII-V semiconductors, MOS technologies in these medium are consideredimmature from a high volume manufacturing (HVM) standpoint.

Another problem with contemporary group III-V technologies stems fromthe lack of reasonably well matched n-type and p-type devices becausealthough group III-V material systems have high electron mobility, holemobility is much lower. As such, a transition from advanced silicon CMOSto group III-V devices may entail a significant disruption to circuitdesign which has to-date co-evolved with silicon-based devices and cometo rely on the availability of complementary transistors for CMOS logic.

Device architectures and fabrication techniques capable of implementingCMOS with group III-V-based microelectronic devices offer the advantageof extending Moore's law for decades more.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are illustrated by way of example,and not by way of limitation, and can be more fully understood withreference to the following detailed description when considered inconnection with the figures in which:

FIG. 1 is an isometric illustration of an NMOS group III-V nanowiretransistor integrated with a PMOS group IV nanowire transistor on a samesubstrate, in accordance with an embodiment;

FIG. 2A is an illustration of a cross-sectional plane passing through achannel region of an NMOS group III-V nanowire transistor integratedwith a PMOS group IV nanowire transistor, in accordance with anembodiment;

FIG. 2B is an illustration of a cross-sectional plane passing through anextrinsic region of an NMOS group III-V nanowire transistor integratedwith a PMOS group IV nanowire transistor, in accordance with anembodiment;

FIG. 3A is an illustration of a cross-sectional plane passing through achannel region of an NMOS group III-V nanowire transistor integratedwith a PMOS group IV nanowire transistor, in accordance with anembodiment;

FIG. 3B is an illustration of a cross-sectional plane passing through anextrinsic region of an NMOS group III-V nanowire transistor integratedwith a PMOS group IV nanowire transistor, in accordance with anembodiment;

FIG. 4A is an illustration of a cross-sectional plane passing through achannel region of an NMOS group III-V nanowire transistor integratedwith a PMOS group IV nanowire transistor, in accordance with anembodiment;

FIG. 4B is an illustration of a cross-sectional plane passing through anextrinsic region of an NMOS group III-V nanowire transistor integratedwith a PMOS group IV nanowire transistor, in accordance with anembodiment;

FIG. 5A is an illustration of a cross-sectional plane passing through achannel region of an NMOS group III-V nanowire transistor integratedwith a PMOS group IV nanowire transistor, in accordance with anembodiment;

FIG. 5B is an illustration of a cross-sectional plane passing through anextrinsic region of an NMOS group III-V nanowire transistor integratedwith a PMOS group IV nanowire transistor, in accordance with anembodiment;

FIG. 6 is a flow diagram illustrating a method of fabricating a NMOSgroup III-V nanowire transistor integrated with a PMOS group IV nanowiretransistor on a same substrate, in accordance with an embodiment;

FIG. 7 is a flow diagram illustrating a method of fabricating a NMOSgroup III-V nanowire transistor integrated with a PMOS group IV nanowiretransistor on a same substrate, in accordance with an embodiment;

FIGS. 8A and 8B are a cross-sectional illustration of startingsubstrates for fabricating a NMOS group III-V nanowire transistorintegrated with a PMOS group IV nanowire transistor, in accordance withan embodiment of the present invention; and

FIG. 9 illustrates a illustrates a computing device in accordance withone implementation of the invention.

DETAILED DESCRIPTION

In the following description, numerous details are set forth, however,it will be apparent to one skilled in the art, that the presentinvention may be practiced without these specific details. In someinstances, well-known methods and devices are shown in block diagramform, rather than in detail, to avoid obscuring the present invention.Reference throughout this specification to “an embodiment” means that aparticular feature, structure, function, or characteristic described inconnection with the embodiment is included in at least one embodiment ofthe invention. Thus, the appearances of the phrase “in an embodiment” invarious places throughout this specification are not necessarilyreferring to the same embodiment of the invention. Furthermore, theparticular features, structures, functions, or characteristics may becombined in any suitable manner in one or more embodiments. For example,a first embodiment may be combined with a second embodiment anywhere thetwo embodiments are not mutually exclusive.

The terms “coupled” and “connected,” along with their derivatives, maybe used herein to describe structural relationships between components.It should be understood that these terms are not intended as synonymsfor each other. Rather, in particular embodiments, “connected” may beused to indicate that two or more elements are in direct physical orelectrical contact with each other. “Coupled” my be used to indicatedthat two or more elements are in either direct or indirect (with otherintervening elements between them) physical or electrical contact witheach other, and/or that the two or more elements co-operate or interactwith each other (e.g., as in a cause an effect relationship).

The terms “over,” “under,” “between,” and “on” as used herein refer to arelative position of one material layer with respect to other layers. Assuch, for example, one layer disposed over or under another layer may bedirectly in contact with the other layer or may have one or moreintervening layers. Moreover, one layer disposed between two layers maybe directly in contact with the two layers or may have one or moreintervening layers. In contrast, a first layer “on” a second layer is indirect contact with that second layer.

Described herein are architectures and techniques for co-integration ofheterogeneous materials, such as group III-V semiconductor materials andgroup IV semiconductors (e.g., Ge) on a same substrate (e.g. silicon).In embodiments, multi-layer heterogeneous semiconductor material stackshaving alternating nanowire and sacrificial layers are employed torelease nanowires and permit formation of a coaxial gate structure thatcompletely surrounds a channel region of the nanowire transistor. Inembodiments, individual PMOS and NMOS channel semiconductor materialsare co-integrated with a starting substrate having a blanket (i.e., fullwafer) stack of alternating Ge/III-V layers. In embodiments, verticalintegration of a plurality of stacked nanowires within an individualPMOS and individual NMOS device enable significant drive current for agiven layout area.

FIG. 1 is an isometric illustration of a PMOS nanowire device(transistor) 110 integrated with a NMOS group III-V nanowire device(transistor) 120 on a same substrate 101, in accordance with anembodiment. The PMOS nanowire device 110 includes one or more PMOSnanowires 112A, 112B composed of a group IV semiconductor disposed overa first substrate region 102, while the NMOS nanowire device 120includes one or more NMOS nanowires 122A, 122B composed of a group III-Vsemiconductor disposed over a second substrate region 103. The differingnanowire materials employed for the PMOS and NMOS devices provide atransistor-level architecture conducive to CMOS with performancecapabilities that beyond silicon-based CMOS devices.

In the illustrative embodiment, the substrate 101 is silicon, insulatingor semi-insulating and/or has an insulating or semi-insulating layerdisposed there on, over which the PMOS device 110 and NMOS device 120 isdisposed. In one such embodiment, the substrate 105 includes a top layerof buffer structure either grown on a support substrate or transferredonto a donor substrate (support and donor substrates not depicted). In aparticular embodiment, the substrate 101 includes a silicon supportsubstrate, upon which a buffer layer is epitaxially grown, however, thesupport substrate may also be of alternate materials, which may or maynot be combined with silicon, including, but not limited to, germanium,indium antimonide, lead telluride, indium arsenide, indium phosphide,gallium arsenide, or gallium antimonide, carbon (SiC), and sapphire. Inanother embodiment, the substrate 101 includes a dielectric layer suchas a buried oxide (BoX) which may be formed for example by transferringone or more layers of the semiconductor from which the nanowires formedonto the substrate 101.

As further illustrated in FIG. 1, for each of the PMOS and NMOS devices110, 120, a longitudinal length of a nanowire is divided between achannel region around which gate conductors 115 and 125 wrap completelyaround to form a coaxial nanowire structure, extrinsic regions aroundwhich dielectric spacers 116A, 116B, 126A, and 126B are disposed, andsource/drain regions 113, 123. Within at least the channel region, thenanowires 112A, 122A are physically separated from the substrate 101 byan intervening material. For the embodiments described herein, thetransverse cross-sectional geometry of the nanowires 112A, 122A may varyconsiderably from circular to rectangular such that the thickness of thenanowires 112A, 122A (i.e., in z dimension) may be approximately equalto a width of the nanowires 112A, 122A (i.e., in x dimension) or thethickness and width of the nanowires 112A, 122A may be significantlydifferent from each other (i.e., physically akin to a ribbon, etc.) toform cylindrical and parallelepiped semiconductor bodies. For ribbonembodiments, advantageous embodiments have a z-dimension larger than thex dimension for the sake of reduced solid angle shadowing by thenanowire thereby improving coaxial encapsulation by the gate conductors115, 125. For the exemplary embodiments, the width of the nanowires112A, 122A is between 5 and 50 nanometers (nm), and more particularlybetween 5 and 10 nm, but this may vary depending on implementation.

Generally, the nanowires 112A, 122A are crystalline with much greaterlong range order than a “polycrystalline” material. In the exemplaryembodiment, the channel region is substantially single crystalline andalthough may be referred to herein as “monocrystalline,” one of ordinaryskill will appreciate that a low level of crystal defects maynevertheless be present as artifacts of an imperfect epitaxial growthprocess. At least one of the PMOS device 110 and NMOS device 120 isheterogeneous in the sense that the substrate 101 is not of the samematerial as at least the channel region of the nanowires 112A and/or122A.

In the exemplary embodiment, the PMOS nanowire 112A consists essentiallyof germanium (Ge). Germanium is advantageous for high hole mobility andalso has lattice parameters matched to some group III-V semiconductormaterials sufficiently for good quality epitaxial stacks of Ge layersand group III-V semiconductor layers. Alternative embodiments where thePMOS nanowire 112A is composed of a group IV alloy (e.g., SiGe) orcomposed of silicon are also possible. In embodiments, the NMOS nanowire122A consists essentially of a group III-V semiconductor material. Inthe exemplary embodiment where the PMOS nanowire 112A consistsessentially of germanium, the NMOS nanowire 122A consists essentially ofGaAs. In other embodiments, the NMOS nanowire 122A consists essentiallyof: InAs, a group III-N (e.g., GaN), InP, a ternary alloy comprisingGaAs, a ternary alloy comprising InAs, a ternary alloy comprising InP,or a ternary alloy comprising a group III-N, or a quaternary alloycomprising GaAs, a quaternary alloy comprising InAs, a quaternary alloycomprising InP, or a quaternary alloy comprising a group III-N. Infurther embodiments, the channel region in both the PMOS nanowire 112Aand the NMOS nanowire 122A is substantially undoped for highest carriermobility.

As further illustrated in FIG. 1, the nanowires 112A, 122A furtherinclude source/drain region 113, 123, respectively. In embodiments, thesource regions comprise the same semiconductor material present in thechannel region for the respective PMOS and NMOS nanowires, but thesource and drain regions further include a higher concentration ofdopant. In the exemplary embodiment, the PMOS nanowire source/drainregion 113 comprises a high p-type impurity (P+ dopant) while the NMOSnanowire source/drain region 123 comprises a high n-type impurity (i.e.,N+ dopant). In certain embodiments, the source and drain regionsmaintain the same monocrystallinity as within the channel region of thenanowires 112A and 123A. In embodiments, at least one of thesource/drains 113, 123 are contacted with an ohmic metal (not depicted)that coaxially wraps completely around the nanowires 112A, 122A to fillin the gaps between the nanowires and the substrate 101. Thesource/drain contacts may further include an epitaxially grownsemiconductor of different composition than the nanowires 112A, 122A.For example, a tunnel junction (e.g., a p+ layer wrapping around thesource region 123 of the nanowire 122A may provide an ultra steep turnon and off (i.e., improved sub-threshold performance). As anotherexample, in-situ doped semiconductor may be grown completely around thereleased source/drains 113, 123 for lower contact resistance.

In embodiments, as shown in FIG. 1, both the PMOS nanowire device 110and the NMOS nanowire device 120 include a vertical stack of nanowiresto achieve a greater current carrying capability (e.g., larger drivecurrents) for a given device footprint (i.e., layout area) over thesubstrate 101. Any number of nanowires may be vertically stacked,depending on fabrication limitations, with the longitudinal axis of eachof the nanowire substantially parallel to a top surface of the substrate101. In the exemplary embodiment illustrated in FIG. 1, within at leastthe channel region, each of the PMOS nanowires 112A, 112B is of the samegroup IV semiconductor material (e.g., Ge). Likewise, within the channelregion each of the NMOS nanowires 122A, 122B is of the same group III-Vsemiconductor material (e.g., GaAs). In further embodiments, each of thePMOS nanowires 112A, 112B is coaxially wrapped by the gate conductor 115(e.g., as further shown in FIGS. 2A, 3A, 4A, 5A). Similarly, for each ofthe stacked nanowires contact metallization and/or raised (regrown)source/drain regions coaxially wrap completely around source/drainregions 113, 123.

FIGS. 2A, 3A, 4A, and 5A illustrate cross-sectional views along an x-zplane (demarked in FIG. 1 by the dashed line A) passing through thechannel regions of the PMOS and NMOS devices 110, 120. FIGS. 2B, 3B, 4B,and 5B illustrate cross-sectional views along an x-z plane (demarked inFIG. 1 by the dashed line B) passing through an extrinsic region of thePMOS and NMOS devices 110, 120.

FIGS. 2A and 2B illustrate an exemplary embodiment where the PMOSnanowires 112A, 112B are substantially coplanar with the NMOS nanowires122A, 122B. As shown for the channel regions depicted in FIG. 2A, alongitudinal axis 153A of the PMOS nanowire 112A is disposed a firstdistance H₁ above the substrate 101 while the longitudinal axis of theNMOS nanowire 122A is disposed a second distance H₂ above the substratethat is substantially equal to H₁ (i.e., less than 10% difference).Furthermore, the pitch P1 between the longitudinal axis 153A, 153B issubstantially equal (i.e., less than 10% different) to the pitch P2between the longitudinal axis of the NMOS nanowires 122A and 122B.

FIG. 2A further illustrates the gate conductors 115 and 125 to eachcomport with the MOS structure of a gate conductor (140, 145) that iselectrically isolated from the nanowires (112, 122) by a gate dielectricmaterial (140, 145) disposed under the gate conductor. The coaxialnature of the wrap-around gate architecture is evident in FIG. 2A as thegate dielectric material is disposed between the substrate layer 100 andthe gate conductor. The gate conductor is also disposed between thenanowires 112A, 122A and the substrate 101. Compositionally, the gatedielectric material 240 may include one or more of any material known inthe art to be suitable for FET gate dielectrics (and/or channelpassivation) and is preferably a high K dielectric (i.e., having adielectric constant greater than that of silicon nitride (Si₃N₄)), suchas, but not limited to, high K oxides like gadolinium oxide (Gd₂O₃),hafnium oxide (HfO₂), high K silicates such as HfSiO, TaSiO, AlSiO, andhigh K nitrides such as HfON.

Similarly, the gate conductor may be of any material known in the artfor gate electrodes suitable for the particular nanowire semiconductorcomposition and desired threshold voltage and operative mode(enhancement or depletion). In certain embodiments the same gatedielectric material is employed for the of the PMOS gate dielectric 140and the NMOS gate dielectric 145. Generally, the gate conductorcomposition includes a work function metal which may be selected to bedistinct for each of the PMOS gate conductor 115 and the NMOS gateconductor 125 to obtain a desired threshold voltage (V_(t)) (e.g.,greater than 0V, etc). Exemplary conductive gate materials include,tungsten (W), aluminum (Al), titanium (Ti), tantalum(Ta), nickel (Ni),molybdenum (Mo), germanium (Ge), platinum (Pt), gold (Au), ruthenium(Ru), palladium (Pd), iridium (Ir), their alloys and silicides,carbides, nitrides, phosphides, and carbonitrides thereof.

Referring to FIG. 2B, in embodiments two vertically stacked nanowiresare physically joined along at least a portion of the longitudinalnanowire length where the spacer is disposed by an intervening thirdcrystalline semiconductor material layer. For example, the PMOS nanowire112A is joined to the substrate 101 by the intervening (third)semiconductor layer 210A while the PMOS nanowires 112A and 112B arejoined together by the intervening semiconductor layer 210B.Analogously, the NMOS nanowire 122A is joined to the substrate 101 bythe intervening (forth) semiconductor layer 220A while the NMOSnanowires 122A and 122B are joined together by the interveningsemiconductor layer 220B. While the structure depicted in FIG. 2B may bein part an artifact of a particular fabrication process where theintervening layers 210, 220 are not completely removed (e.g., masked bythe spacers 116A, 126A), it nonetheless illustrates the semiconductormaterial stack employed to release the nanowires in the channel regionsdepicted in FIG. 2A.

Generally, the intervening semiconductor layers 210A, 210B are of anysacrificial semiconductor material which can maintain the desiredcrystallinity of the PMOS nanowires 112A, 112B and are amenable to beingremoved selectively to the PMOS nanowires 112A, 112B. In the exemplaryembodiment where the PMOS nanowires 112A, 112B are Ge, the sacrificialsemiconductor layers 210A, 210B comprise SiGe. Likewise, the interveningsemiconductor layers 220A, 220B are of any sacrificial semiconductormaterial which can maintain the desired crystallinity of the NMOSnanowires 122A, 122B and are amenable to being removed selectively tothe PMOS nanowires 112A, 112B. In one exemplary embodiment where theNMOS nanowires 122A, 122B are GaAs, the sacrificial semiconductor layers220A, 220B comprise AlGaAs. Notably, the thicknesses (z-dimension) ofthe sacrificial semiconductor layers 210, 220 may be selected as amatter of design based on desired nanowire pitch (e.g., P1, P2), gatestack deposition constraints, stack profile control, etc.

FIGS. 3A and 3B illustrate an exemplary embodiment where the PMOSnanowires 112A, 112B are shifted or offset along the z-dimension fromthe NMOS nanowires 122A, 122B. As shown for the channel regions depictedin FIG. 3A, the longitudinal axis of the PMOS nanowire 112A is disposeda first distance H₁ above the substrate 101 while the longitudinal axisof the NMOS nanowire 122A is disposed a second distance H₂ above thesubstrate that is different than H₁ (i.e., significantly more than 10%different). In the illustrative embodiment, second distance H₂ isapproximately equal to the first distance H₁ added to a thickness of thefirst channel region (z-dimension) because the nanowires 112A and 122Aare substantially equal. As also shown, the gap G₁ between adjacent PMOSnanowires 112A, 112B is substantially equal to the thickness (diameter)of the NMOS nanowire 122A (illustrated as T₃ in FIG. 3B). The gap G₂between adjacent NMOS nanowires 122A, 122B is substantially equal to thethickness (diameter) of the PMOS nanowire 112B (illustrated as T₄ inFIG. 3B). As such, the pitches P1 and P2 are substantially equal.

As further illustrated in FIG. 3B, within the extrinsic regions, thesemiconductor material stack for the PMOS device 110 is the same as forthe NMOS device 120. In essence, the group IV material in the PMOSnanowire (e.g., 112B) serves as a sacrificial material in the NMOSdevice 120 while the group III-V material in the NMOS nanowire (e.g.,122A) serves as a sacrificial material in the PMOS device 110. In theexemplary embodiment, both the PMOS device 110 and the NMOS device 120include a group IV semiconductor (e.g., Ge) layer alternating with agroup III-V semiconductor (e.g., GaAs). This dual function of thesemiconductor layers is advantageous because it permits the PMOS/NMOSpair of stacks to be formed from a same blanket process thatconcurrently covers both the first and second regions of the substrate(e.g., regions 102 and 103 in FIG. 1).

Also shown in the embodiment of FIGS. 2A, 2B, the PMOS nanowire 112 isdisposed apart from the substrate 101 by way of a third sacrificialsemiconductor material 210A that is also present in the NMOS devicestack. The third sacrificial material semiconductor 210A, as for FIGS.2A, 2B, provides a standoff for the nanowire disposed closest to thesubstrate (e.g., PMOS nanowire 112A) to permit a wrap-around gate stack.Employed as depicted in FIGS. 2A and 2B, the third sacrificialsemiconductor material 210A may be removed selectively to both the PMOSnanowire 112A and the NMOS nanowire 122A. For example, in one embodimentthe third sacrificial semiconductor material 210A is group IVsemiconductor (SiGe) while in another embodiment the third sacrificialsemiconductor material 210A is a group III-V semiconductor material(AlGaAs). In other embodiments, the third sacrificial semiconductormaterial may be left as a non-functional, structural artifact in thedevice does not rely on the third sacrificial material as a means ofnanowire release from the substrate 101 (e.g., the third sacrificialsemiconductor material 210A may be left in the NMOS device 120) suchthat selectivity of the third sacrificial semiconductor material 210A tothe group III-V material in nanowire 122A poses no issue.

FIGS. 3A and 3B illustrate an exemplary embodiment where the PMOSnanowires 112A, 112B are again substantially offset from the NMOSnanowires 122A, 122B along the z-dimension. In the third exemplaryembodiment, a third sacrificial layer is disposed between adjacentlayers in the alternating semiconductor material stacks as a means ofdecoupling the vertical spacing between nanowires in a first device(e.g., PMOS device 110) from the cross-sectional dimension (e.g.,diameter or thickness in z-dimension) of a nanowire in the second device(e.g., NMOS device 120).

As illustrated in FIG. 4A, the gap G₁ between adjacent PMOS nanowires112A, 112B is larger than the thickness of the NMOS nanowire 122A (T₃,FIG. 4B) and the gap G₂ between adjacent NMOS nanowires 122A, 122B islarger than the thickness of the PMOS nanowire 112B (T₄, FIG. 4B). Thelarger gaps G1, G2 may be tailored to the demands of channel engineeringand/or gate stack deposition constraints to ensure adequate fill of thegate conductors 115, 125 around the nanowires 112A, 112B, 122A, 122B. Asfurther shown in FIG. 4B, a third sacrificial semiconductor material310A is disposed between the nanowires 122A, 112B. In this embodiment,the third sacrificial semiconductor material 310A is again removedselectively to both the group IV material employed in the PMOS nanowire112B and the group III-V material employed in the NMOS nanowire 122A.While many such materials exist, the preferred materials are conduciveto maintaining crystallinity of the group III-V and group IV materials,for example SiGe, or AlGaAs.

FIGS. 4A and 4B further illustrate an exemplary embodiment where arecess etching the substrate 101 enables release of a nanowire (e.g.,the PMOS nanowire 112A) without a third sacrificial layer disposed onthe substrate 101. As shown, the substrate 101 has a recess of height ΔHsufficient to release the PMOS nanowire 112A. The portion of the recessunder the channel region is backfilled with gate conductor 115. Such astructure may be achieved by undercutting the device stack in the firstsubstrate region 102 with an etchant selective to the substratematerial. With the substrate 101 recessed selectively in one of thesubstrate regions, the PMOS and NMOS devices 110, 120 may be formed froma same semiconductor devices stack with minimal vertical stack height.

FIGS. 5A and 5B illustrate an exemplary embodiment where a plurality ofmaterials is employed in a nanowire of a first device. That plurality ofmaterials is then either sacrificial in the second device or retained.As shown in FIG. 5A, the NMOS device 120 includes a nanowire 122A with abottom and top barrier or transition layer 132A, 132B and a nanowire122B with a bottom and top barrier or transition layer 142A, 142B. Thebarrier or transition layers 132A, 132B, 142A, 142B may be of adifferent bandgap (e.g., wider) than the nanowires 122A, 122B and mayfunction as one or more of, a hybrid gate dielectric layer confiningcarriers in combination with the gate dielectric 145, a channelpassivation layer, a sheet charge inducing layer, a strain layer, achannel bandgap (V_(t)) tuning layer, or the like.

As shown in FIG. 3B, the barrier or transition layers 132A, 132B, 142A,142B are present in extrinsic regions of both the PMOS and NMOS devices110, 120, and may either be utilized as sacrificial layer or retained asa partial cladding in the channel region of the complementary device.For example, the barrier or transition layers 132A, 132B, 142A, 142B maybe utilized in the PMOS device 110 in one of the functional capacitiesdescribed above for the NMOS device 120. However, in the embodimentillustrated by FIG. 5A, the barrier or transition layers 132A, 132B,142A, 142B are removed from the PMOS nanowires 112A, 112B as sacrificialalong with the group III-V semiconductor utilized for the NMOS nanowires122A, 122B. In this exemplary embodiment, the larger gap G₁ resultingfrom removing the barrier or transition layers 132A, 132B then providesmore room for a separate channel transition layer 138, which like thegate dielectric 140 and gate conductor 115, may wrap around the PMOSnanowires 112A, 112B. Likewise, a larger gap G2 is provided by removingbarrier or transition layers 142A, 142B.

A brief description of salient portions of fabrication processembodiments is now provided. FIGS. 6 and 7 are flow diagram illustratingmethods 601 and 701 of fabricating a NMOS group III-V nanowiretransistor integrated with a PMOS group IV nanowire transistor on a samesubstrate, in accordance with embodiments of the present invention.While methods 601 and 701 highlight certain operations, those operationsmay entail many more process sequences, and no order is implied by thenumbering of the operations or relative positioning of the operations inFIGS. 6 and 7. Generally, the method 601 utilizes a starting substratehaving a blanket deposited semiconductor stack that is the same in tworegions of the substrate 810, 820, as illustrated in FIG. 8A, while themethod 701 entails a starting substrate having materially distinctstacks disposed in the two regions of the substrate 810, 820.

Referring first to FIG. 6, the method 601 begins at operation 610 withan alternating stack of PMOS and NMOS semiconductor material layersdisposed on the first and second regions of the substrate. For example,in the illustrative embodiment depicted in FIG. 8A, the startingsubstrate 801 has a same stack of semiconductor materials 803 in whichgroup IV semiconductor layers alternate with group III-V semiconductorlayers disposed over both the regions 810 and 820. The alternating stackof semiconductor materials 803 may be epitaxially grown on the substrate101 or transferred and bonded.

Subsequently, at operation 620 the stack 803 is etched, for example byanisotropic plasma etch, into a first fin in the first region 810 and asecond fin in the second region 820. Depending on the group IV and groupIII-V materials, one or more plasma etch processes based on conventionaltechniques may be utilized. At operation 630, NMOS material is removedfrom the first fin to form a gap between the group IV semiconductorlayer and the substrate 101 to release the PMOS nanowires along alongitudinal channel length. For example, in the starting material 801(FIG. 8A) the group III-V layers are removed within the first region 810selectively to the group IV layers using conventional techniques (e.g.,isotropic wet and/or dry etch chemistries) to release PMOS nanowires112A, 112B. At operation 640, PMOS material is removed from the secondfin selectively to the group III-V semiconductor layer to form a gapbetween the group III-V semiconductor layer and the substrate to releasethe NMOS nanowires along at least their longitudinal channel lengths.For example, in the stack 803 (FIG. 8A), within the second region 820,the group IV layers are removed selectively to the group III-V layers torelease the NMOS nanowires 122A and 122B.

At operation 650, gate stacks are then formed completely around the PMOSand NMOS nanowires (i.e., a coaxial structure) using any conventionaldeposition technique as a function of the materials utilized. Inparticular embodiments, replacement gate techniques are utilized, asknown in the art for non-planar silicon transistor technologies. In oneembodiment, a sacrificial gate (stack) is formed, source and drainregions in the nanowires 112A, 112B are doped p-type, and source anddrain regions in the nanowires 122A, 122B are doped n-type (and/orwrapped with raised source drain regions), the sacrificial gate removed,and the non-sacrificial gate stack formed. Exemplary techniques forforming the non-sacrificial gate include atomic layer deposition (ALD)for high-K gate dielectric material, and ALD or physical vapordeposition (PVD) for gate conductor materials. Method 601 is thencompleted at operation 660 with conventional processing (e.g.,interlayer dielectric formation, source and drain contact formation oneach of the PMOS and NMOS devices, etc.).

Referring next to FIG. 7, the method 701 begins at operation 715 with afirst stack of alternating PMOS semiconductor material layers and afirst sacrificial material disposed on the first region of the substrateand a second stack of alternating NMOS semiconductor material layers anda second sacrificial material disposed on the second region of thesubstrate. For example, in the illustrative embodiment depicted in FIG.8B, the starting material 802 includes a first stack of semiconductormaterials 804, with the group IV semiconductor layers alternating withfirst sacrificial material layers 210A, 210B, disposed over a firstsubstrate region 810. The starting material 802 further includes asecond stack of semiconductor materials 805, with the group III-Vsemiconductor layers alternating with second sacrificial semiconductormaterial 220A, 220B, disposed over the second substrate region 820. Forthis embodiment, each distinct alternating stack of semiconductormaterials may be epitaxially grown on the substrate 101 (e.g., in thetrenches formed in field isolation dielectric layer 850) and thensidewalls of the materials exposed (e.g., by recessing the fieldisolation dielectric layer 850).

At operation 725 the first sacrificial material layers 210A, 210B areremoved by an etchant selective over the group IV semiconductormaterials to form the PMOS nanowires 112A, 112B to release the PMOSnanowires 112A, 112B. At operation 735, the second sacrificial materiallayers 220A, 220B are removed by an etchant selective over the groupIII-V semiconductor layers to release the NMOS nanowires 122A, 122B. Atoperation 745 gate stacks are formed completely around the releasedchannel regions of the PMOS and NMOS nanowires (i.e., workfunctionmetals forming a coaxial structure with the nanowires) using anyconventional deposition technique as a dependent on the workfunction andcapping materials utilized. In particular embodiments, replacement gatetechniques are utilized, as known in the art for non-planar silicontransistor technologies. In one embodiment, a sacrificial gate (stack)is formed, source and drain regions in the nanowires 112A, 112B aredoped p-type, and source and drain regions in the nanowires 122A, 122Bare doped n-type (and/or wrapped with raised source drain regions), thesacrificial gate removed, and the non-sacrificial gate stack formed.Method 701 is then completed at operation 660 with conventionalprocessing (e.g., interlayer dielectric formation, source and draincontact formation on each of the PMOS and NMOS devices, etc.).

In either method 601 or 701 it is understood that the semiconductorstacks disposed on the substrate may further include one or more of theintervening semiconductor layers described elsewhere herein (e.g., byepitaxially growing a third sacrificial layer over the substrate in thefirst and second regions 810, 820). For such embodiments, operations 620and 725 then further include etching the third sacrificial layerselectively to the group IV semiconductor layer to form a gap betweenthe group IV semiconductor layer and the substrate in the first region810 that is wider than a thickness of the group III-V semiconductorlayer. Similarly, the third sacrificial layer is further etchedselectively to the group III-V semiconductor layer to form a gap betweenthe group III-V semiconductor layer and the substrate in the secondregion 820 that is wider than a thickness of the group IV semiconductorlayer.

FIG. 9 illustrates a computing device 1000 in accordance with oneimplementation of the invention. The computing device 1000 houses aboard 1002. The board 1002 may include a number of components, includingbut not limited to a processor 1004 and at least one communication chip1006. The processor 1004 is physically and electrically coupled to theboard 1002. In some implementations the at least one communication chip1006 is also physically and electrically coupled to the board 1002. Infurther implementations, the communication chip 1006 is part of theprocessor 1004.

Depending on its applications, computing device 1000 may include othercomponents that may or may not be physically and electrically coupled tothe board 1002. These other components include, but are not limited to,volatile memory (e.g., DRAM), non-volatile memory (e.g., ROM), flashmemory, a graphics processor, a digital signal processor, a cryptoprocessor, a chipset, an antenna, a display, a touchscreen display, atouchscreen controller, a battery, an audio codec, a video codec, apower amplifier, a global positioning system (GPS) device, a compass, anaccelerometer, a gyroscope, a speaker, a camera, and a mass storagedevice (such as hard disk drive, compact disk (CD), digital versatiledisk (DVD), and so forth).

The communication chip 1006 enables wireless communications for thetransfer of data to and from the computing device 1000. The term“wireless” and its derivatives may be used to describe circuits,devices, systems, methods, techniques, communications channels, etc.,that may communicate data through the use of modulated electromagneticradiation through a non-solid medium. The term does not imply that theassociated devices do not contain any wires, although in someembodiments they might not. The communication chip 1006 may implementany of a number of wireless standards or protocols, including but notlimited to Wi-Fi (IEEE 802.11 family), WiMAX (IEEE 802.16 family), IEEE802.20, long term evolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE,GSM, GPRS, CDMA, TDMA, DECT, Bluetooth, derivatives thereof, as well asany other wireless protocols that are designated as 3G, 4G, 5G, andbeyond. The computing device 1000 may include a plurality ofcommunication chips 1006. For instance, a first communication chip 1006may be dedicated to shorter range wireless communications such as Wi-Fiand Bluetooth and a second communication chip 1006 may be dedicated tolonger range wireless communications such as GPS, EDGE, GPRS, CDMA,WiMAX, LTE, Ev-DO, and others.

The processor 1004 of the computing device 1000 includes an integratedcircuit die packaged within the processor 1004. In some implementationsof the invention, the integrated circuit die of the processor includesone or more devices, such as the PMOS device 110 and NMOS device 120(FIG. 1) in accordance with embodiments described elsewhere herein. Theterm “processor” may refer to any device or portion of a device thatprocesses electronic data from registers and/or memory to transform thatelectronic data into other electronic data that may be stored inregisters and/or memory.

The communication chip 1006 also includes an integrated circuit diepackaged within the communication chip 1006. In accordance with anotherimplementation of the invention, the integrated circuit die of thecommunication chip includes one or more devices, such as the PMOS device110 and NMOS device 120 (FIG. 1) in accordance with embodimentsdescribed elsewhere herein.

In further implementations, another component housed within thecomputing device 1000 may contain an integrated circuit die thatincludes one or more devices, such as the PMOS device 110 and NMOSdevice 120, as illustrated in FIG. 1 and described elsewhere herein.

In various implementations, the computing device 1000 may be a laptop, anetbook, a notebook, an ultrabook, a smartphone, a tablet, a personaldigital assistant (PDA), an ultra mobile PC, a mobile phone, a desktopcomputer, a server, a printer, a scanner, a monitor, a set-top box, anentertainment control unit, a digital camera, a portable music player,or a digital video recorder. In further implementations, the computingdevice 1000 may be any other electronic device that processes data.

It is to be understood that the above description is illustrative, andnot restrictive. For example, while flow diagrams in the figures show aparticular order of operations performed by certain embodiments of theinvention, it should be understood that such order may not be required(e.g., alternative embodiments may perform the operations in a differentorder, combine certain operations, overlap certain operations, etc.).Furthermore, many other embodiments will be apparent to those of skillin the art upon reading and understanding the above description.Although the present invention has been described with reference tospecific exemplary embodiments, it will be recognized that the inventionis not limited to the embodiments described, but can be practiced withmodification and alteration within the spirit and scope of the appendedclaims. The scope of the invention should, therefore, be determined withreference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

What is claimed is:
 1. A pair of semiconductor devices, comprising: afirst nanowire disposed over a substrate, wherein a longitudinal lengthof the first nanowire further comprises: a first channel region of agroup IV semiconductor material; a first source region and a first drainregion electrically coupled with the first channel region; a first gatestack comprising a gate insulator and a gate conductor coaxiallywrapping completely around the first channel region; and a secondnanowire disposed over the substrate, the second nanowire furthercomprising: a second channel region of a group III-V semiconductormaterial; a second source region and second drain region electricallycoupled with the second channel region; and a second gate stackcomprising a gate insulator and a gate conductor coaxially wrappingcompletely around and in continuous contact with the group III-Vsemiconductor materials of the second channel region.
 2. The pair ofsemiconductor devices of claim 1, wherein the first source region andfirst drain region are p-type, and wherein the second source region andsecond drain region are n-type to render the pair of semiconductordevices complementary.
 3. The pair of semiconductor devices of claim 1,wherein the group IV semiconductor material consists essentially ofgermanium (Ge).
 4. The pair of semiconductor devices of claim 1, whereinthe longitudinal axis of the first channel region is disposed a firstdistance above the substrate and wherein the longitudinal axis of thesecond channel region is disposed a second distance above the substratethat is different from first distance.
 5. The pair of semiconductordevices of claim 1, wherein the second distance is at least equal to thefirst distance added to a thickness of the first channel region along adirection orthogonal to the substrate.
 6. The pair of semiconductordevices of claim 1, wherein the first nanowire is disposed within afirst vertical stack of nanowires, wherein each nanowire in the firstvertical stack has a channel region consisting essentially of the groupIV material, and wherein two adjacent nanowires in the first verticalstack are physically joined at a location along the longitudinal lengthby an intervening crystalline semiconductor material different than thegroup IV material.
 7. The pair of semiconductor devices of claim 6,wherein the intervening crystalline semiconductor material is disposedwithin a spacer region adjacent to the first gate stack.
 8. The pair ofsemiconductor devices of claim 6, wherein the intervening crystallinesemiconductor material is the group III-V semiconductor material.
 9. Thepair of semiconductor devices of claim 8, wherein the second nanowire isdisposed within a second vertical stack of nanowires, wherein eachnanowire in the second vertical stack has a channel region consistingessentially of the group III-V semiconductor material, and wherein twoadjacent nanowires in the second vertical stack are physically joined ata location along the longitudinal length by a second interveningcrystalline semiconductor material different than the group III-Vsemiconductor.
 10. The pair of semiconductor devices of claim 9, whereinthe intervening crystalline semiconductor material is the group III-Vsemiconductor material and wherein the second intervening crystallinesemiconductor material is the group IV semiconductor material.
 11. Thepair of semiconductor devices of claim 10, wherein the two adjacentnanowires in the first vertical stack and the two adjacent nanowires inthe second vertical stack are physically joined at a location along thelongitudinal length by a third intervening crystalline semiconductormaterial that is different than either the group IV or group III-Vsemiconductor material.
 12. The pair of semiconductor devices of claim11, wherein the third intervening crystalline semiconductor material isa group IV semiconductor material.
 13. The pair of semiconductor devicesof claim 12, wherein the third intervening crystalline semiconductormaterial is SiGe.
 14. A pair of complementary transistors, comprising: ap-type transistor disposed over a substrate, wherein a longitudinallength of the p-type transistor further comprises: a first channelregion of a group IV semiconductor material; a p-type source and drainregion electrically coupled with the first channel region; a first gatestack comprising a gate insulator and a gate conductor coaxiallywrapping completely around the first channel region; and an n-typetransistor disposed over the substrate, wherein a longitudinal length ofthe n-type transistor further comprises: a second channel region of agroup III-V semiconductor material; an n-type source and drain regionelectrically coupled with the first channel region; and a second gatestack comprising a gate insulator and a gate conductor coaxiallywrapping completely around and in continuous contact with the groupIII-V semiconductor material of the second channel region.
 15. The pairof complementary transistors wherein the group IV semiconductor materialconsists essentially of germanium (Ge) and wherein the group III-Vsemiconductor material consists essentially of one of: GaAs, InAs, InP,and a group III-N.
 16. A pair of semiconductor devices, comprising: afirst nanowire disposed over a substrate, wherein a longitudinal lengthof the first nanowire further comprises: a first channel region of agroup IV semiconductor material; a first source region and a first drainregion electrically coupled with the first channel region; a first gatestack comprising a gate insulator and a gate conductor coaxiallywrapping completely around the first channel region; and a secondnanowire disposed over the substrate, the second nanowire furthercomprising: a second channel region of a group III-V semiconductormaterial; a second source region and second drain region electricallycoupled with the second channel region; and a second gate stackcomprising a gate insulator and a gate conductor coaxially wrappingcompletely around the second channel region, wherein the first nanowireis disposed within a first vertical stack of nanowires, wherein eachnanowire in the first vertical stack has a channel region consistingessentially of the group IV material, and wherein two adjacent nanowiresin the first vertical stack are physically joined at a location alongthe longitudinal length by an intervening crystalline semiconductormaterial different than the group IV material wherein the interveningcrystalline semiconductor material is disposed within a spacer regionadjacent to the first gate stack.
 17. The pair of semiconductor devicesof claim 16, wherein the first source region and first drain region arep-type, and wherein the second source region and second drain region aren-type to render the pair of semiconductor devices complementary. 18.The pair of semiconductor devices of claim 16, wherein the group IVsemiconductor material consists essentially of germanium (Ge).
 19. Thepair of semiconductor devices of claim 16, wherein the longitudinal axisof the first channel region is disposed a first distance above thesubstrate and wherein the longitudinal axis of the second channel regionis disposed a second distance above the substrate that is different fromfirst distance.
 20. The pair of semiconductor devices of claim 19,wherein the second distance is at least equal to the first distanceadded to a thickness of the first channel region along a directionorthogonal to the substrate.
 21. A pair of semiconductor devices,comprising: a first nanowire disposed over a substrate, wherein alongitudinal length of the first nanowire further comprises: a firstchannel region of a group IV semiconductor material; a first sourceregion and a first drain region electrically coupled with the firstchannel region; a first gate stack comprising a gate insulator and agate conductor coaxially wrapping completely around the first channelregion; and a second nanowire disposed over the substrate, the secondnanowire further comprising: a second channel region of a group III-Vsemiconductor material; a second source region and second drain regionelectrically coupled with the second channel region; and a second gatestack comprising a gate insulator and a gate conductor coaxiallywrapping completely around the second channel region, wherein the firstnanowire is disposed within a first vertical stack of nanowires, whereineach nanowire in the first vertical stack has a channel regionconsisting essentially of the group IV material, and wherein twoadjacent nanowires in the first vertical stack are physically joined ata location along the longitudinal length by an intervening group III-Vcrystalline semiconductor material different than the group IV material,wherein the second nanowire is disposed within a second vertical stackof nanowires, wherein each nanowire in the second vertical stack has achannel region consisting essentially of the group III-V semiconductormaterial, and wherein two adjacent nanowires in the second verticalstack are physically joined at a location along the longitudinal lengthby a second intervening crystalline semiconductor material differentthan the group III-V semiconductor, wherein the intervening crystallinesemiconductor material is the group III-V semiconductor material andwherein the second intervening crystalline semiconductor material,wherein the two adjacent nanowires in the first vertical stack and thetwo adjacent nanowires in the second vertical stack are physicallyjoined at a location along the longitudinal length by a thirdintervening crystalline semiconductor material that is different thaneither the group IV or group III-V semiconductor material.
 22. The pairof semiconductor devices of claim 21, wherein the group IV semiconductormaterial consists essentially of germanium (Ge).
 23. The pair ofsemiconductor devices of claim 21, wherein the longitudinal axis of thefirst channel region is disposed a first distance above the substrateand wherein the longitudinal axis of the second channel region isdisposed a second distance above the substrate that is different fromfirst distance.
 24. The pair of semiconductor devices of claim 23,wherein the second distance is at least equal to the first distanceadded to a thickness of the first channel region along a directionorthogonal to the substrate.
 25. The pair of semiconductor devices ofclaim 21, wherein the third intervening crystalline semiconductormaterial is a group IV semiconductor material.
 26. The pair ofsemiconductor devices of claim 25, wherein the third interveningcrystalline semiconductor material is SiGe.